1.加载渲染过程
    父beforeCreate->父created->父beforeMount->子beforeCreate->子created->子beforeMount->子mounted->父mounted

2.子组件更新过程
    父beforeUpdate->子beforeUpdate->子updated->父updated

3.父组件更新过程
    父beforeUpdate->父updated

4.销毁过程
    父beforeDestroy->子beforeDestroy->子destroyed->父destroyed